The Consolidated B-36 Peacekeeper was developed in response to the early German victories in 1939-40, but development was slow, and it ended up being Strategic Air Command's main long range bomber during the 1950s.
The B-36 was developed in response to a USAAF specification of 11 April 1941 for a bomber capable of hitting targets in mainland Europe from bases in the United States, issued when a German invasion of the United Kingdom was still a real possibility. The first version of the specifications called for an aircraft with a top speed of 450mph, a cruising speed of 275mph, a range of 12,000 miles and a ceiling of 45,000ft. This was soon scaled down to a range of 10,000 miles, cruising speed of 240-300mph and ceiling of 40,000ft, but that was still more than enough to reach Germany from the US East Coast and return. The new aircraft was to have a maximum payload of 72,000lb or 10,000lb for the trip to Europe.
Consolidated submitted its design on 3 May 1941, alongside Boeing, Douglas and Northrop. On 15 November Consolidated was given a contract to build two prototypes of the XB-36, to be delivered in May and November 1944. Work began at San Diego, but soon moved to Forth Worth because the San Diego plant was already busy with various flying boats and the B-24 Liberator.
Consolidated's design was massive. It had slightly swept back wings with a span of 230ft and a thickness of 6ft at the root to allow for access to the engines from within the wings. The original design used six Pratt & Whitney R-4360 Wasp Major air cooled radial engines, driving pusher propellers (the pusher configuration was adopted in order to improve air flow over the wings, which was disrupted by tractor propellers). The Wasp Major was created by combining two fourteen cylinder Twin Wasp engines. The fuselage was 162ft long, and included an 80ft long pressurized tunnel to allow the crew to move from the front to the rear on a wheeled trolley. This connected the pressurized cabin in the nose to a rear compartment containing bunks and the rear gunners positions. The first design, the Model 35, had twin fins and rudders, similar to the much smaller Consolidated B-24 Liberator. This was later replaced with a large single tail, which gave the aircraft its height of almost 47ft. The defensive armament changed several times, but eventually a layout with eight remotely controlled turrets, each with two 20mm cannon, was adopted. The 230ft long wings had a crawl-way inside to allow the flight engineer to reach the engines while the aircraft was in flight.
In June 1943 an order was placed for 100 aircraft, with the prototype to be ready by September 1944. At this point the new target was Japan - Britain was clearly safe from invasion, with the Germans bogged down in Russia and a powerful US army building up for the invasion of mainland Europe, but in China the Japanese advance threatened to capture the areas that the USAAF intended to use as B-29 bases for attacks on the Japanese Home Islands.
Work on the B-36 was slower than hoped. The engines caused problems, and as the Allies advanced across the Pacific the need for bases in China faded and the B-29 had the range required to attack Japan from the newly captured island bases. The B-36 survived because it had the potential to carry the very heavy atomic bombs on long range raids.
The prototype XB-36 finally rolled out at Fort Worth on 8 September 1945, one year after it was meant to have made its maiden flight, and didn't take to the air until 8 August 1946. By this time it had a new single vertical tail, and at the time was the largest and heaviest land based aircraft ever to have flown. Only three runways in the United States could actually take its weight, which required 22 inches of concrete (this improved after new four wheel bogies replaced the single wheels, reducing the requirement to 13.5in).
The first production aircraft made its maiden flight on 27 August 1947, but only to go to Wright Field to destruction testing. The second prototype made its maiden flight on 4 December 1947. It had a new raised cockpit canopy to improve visibility. It was built with the original single wheeled undercarriage, but later got the four wheel bogies.
The last of 383 B-36s was delivered on 14 August 1954. It was produced in a number of variants. The B-36A was an unarmed trainer. The B-36B was the first bomber version. The B-36D saw the addition of four turbojets mounted outboard of the piston engines, improving the aircraft's performance. The RB-36E was a reconnaissance version of the B-36D. The B-36E was the B-36A and B-36B when converted to B-36D standard. The B-36F was similar to the B-36B but with more powerful engines. The B-36H had an improved flight deck. The B-36J had extra fuel and stronger landing gear.
The B-36 entered service with the 7th Bomb Group (Heavy) in June 1948. The 7th BG was joined by the 11th BG (H) later in the year. By this point the B-36 was already almost obsolete. Tests in 1949-50 showed that the Navy's F9F Panther and F2H Banshee could both intercept the B-36, which was so large that it appeared on the limited airborne radar of the period, too slow to avoid the fighters, and only defended by cannon, making it vulnerable to missile attacks, which would come from well outside gun range. The jet boosted versions of the B-36 were faster, but by the time they appeared so were fighters.
The B-36 was the main part of Strategic Air Command's deterrent force until 1958, when it began to be replaced by the B-52. At its peak the B-36 equipped ten bomber wings, which had 209 B-37s and 133 RB-36s. The units involved were the 5th Bomber Wing (Travis, California), 6th (Walker, New Mexico), 7th and 11th (Carswell, Texas), 28th (North Dakota), 42nd (Loring, Maine), 72nd (Ramey, Puerto Rico), 92nd and 99th (Fairchild, Washington) and 95th (Biggs, Texas). The aircraft's heyday was short - in 1955 it began to be replaced by the B-52, and the last was withdrawn from front line service on 12 February 1959.
The bomber versions saw no combat service, but the reconnaissance aircraft were used for flights close to Soviet territory, and may well have crossed Soviet air space on occasions.
The B-36 was the largest bomber ever to see service with the USAF. It dwarfed the wartime B-29, with a maximum payload four times larger, the ability to carry 10,000lb of bombs twice as far as the B-29's maximum range and was90ft wider, 60ft longer and 19ft taller.
The B-36 set a number of records. On 29 January 1949 one carried two dummy 42,000lb Grand Slam bombs, setting a bomb load record. On 7-8 December 1948 one made a round-trip to Hawaii from the US west coast in 35.5 hours. In March 1949 a B-36 set a long distance record of 9,600 miles in 43hr 37min.
The B-36A was the first production version, and was an unarmed training aircraft. The first made its maiden flight on 28 August 1947, but was then tested to destruction. Twenty two were built in total, of which nineteen went to the 7th Bomb Group (Heavy) at Carswell AFB, starting in June 1948.
The first armed version was the B-36B, of which 62 were built. These were powered by six 3,500hp Pratt & Whitney R-4360-41 engines, and had a gross weight of 328,000lb. They were armed with six retractable turrets armed with two 20mm cannon and two more cannon in the nose. The first made its maiden flight on 8 July 1948.
By the time the B-36B entered service its weight had increased faster than its engine power, and it was being outperformed by less expensive aircraft. Convair's first answer was to use a 4,300hp variable discharge turbine version of the R-4360. This used the exhaust gases from the engine to pass through a turbo supercharger, before emerging as thrust, potentially producing another 800hp per engine. However this would have required a change to a tractor layout, as the VDT wasn't compatible with pusher propellers. Convair suggested converting 34 from the original 100 aircraft to the new layout, and reducing the overall order by five to pay for it, but the VDT engine failed.
The speed problem was eventually fixed by installed four turbojet engines in pods carried below the wing and outside the outer piston engines, producing the 'six turning and four burning' layout. The prototype of this layout made its maiden flight on 26 March 1949, using Allison J35-A-19 turbojets. Production aircraft used a more powerful 5,200lb thrust General Electric J47-GE-19 engine, and the first of these made its maiden flight on 11 July 1949.
The extra engines allowed the maximum take-off range to rise to 358,000lb and the payload to 84,000lb. The crew almost doubled, to 15, to allow a spare crew to be carried. The new design could reach 406mph at 36,000ft. twenty six B-36Ds were built from new and another 59 converted from B-36Bs, almost all of the original production run.
The RB-36D was a reconnaissance version of the R-36D. These aircraft carried a crew of twenty two, and had fourteen cameras in the bomb bay, along with extra fuel tanks to bring the endurance up to 50 hours. Deliveries started from 3 June 1950 and a total of 24 were completed - 17 from new and 7 by converting B-36Bs.
Recon version of the -36D
The RB-36E was the designation given to twenty-one B-36As (all but one of the entire production run) and the single YB-37 after they were converted to the RB-36D standard, with the same camera equipment, and turbojets added to their original piston engines.
The B-36F was similar to the B-36D, but with more powerful 3,800hp R-4360-53 engines. The first one made its maiden flight on 18 November 1950. A total of 58 were produced - 34 as bombers and 24 as the RB-36F reconnaissance version. All had improved ECM equipment.
Twenty four of the B-36Fs were completed as reconnaissance aircraft, with similar cameras to the RB-36D.
The GRB-36F was the designation given to aircraft converted to carry a small escort fighter in its bomb bay as part of the FICON programme (Fighter-Conveyer). One aircraft was converted in 1951-52, and tested with a Republic F-84. The fighter was attached to trapeze equipment, and could be launched and retrieved in mid air. The first retrieval was carried out on 23 April 1952 and the first composite flight, with the fighter in place from the start, on 14 May. In May 1953 another ten were ordered. They were to carry a RF-84K on a H-shaped cradle in the bomb bay. By now the idea had changed from providing fighter defence to improving the range of reconnaissance. Trials were carried out at Fairchild AFB but the scheme was abandoned after a year. One GRB-36F was also used to test out the TomTom concept, in which a pair of RF-84Fs were towed into a combat zone on hooks carried on the tips of the bomber's wings. This proved to be rather dangerous, and was soon abandoned.
The designation B-36G was given to a design for a version of the aircraft with wept wings and turbojet engines only. This was eventually developed as the YB-60.
The B-36H had an improved cockpit and other internal changes. The first made its maiden flight on 5 April 1952. A total of 156 were built, of which 83 were delivered as B-36H bombers and 73 as RB-36H reconnaissance aircraft. One of the B-36Hs was later converted into the NB-36H, which carried a nuclear reactor and was used for tests of radiation shielding and on the effects of radiation on equipment and airframes. The NB-36H made its maiden flight on 17 September 1955.
The B-36J was the final production version. It carried an extra 2,770 gallons of fuel in the outer wings and had stronger landing gear. It could operate at a gross weight of 410,000lb. Thirty three were built between September 1943 and August 1954. The last fourteen had all but the tail guns removed.
One example of a transport version was completed as the massive XC-99
The X-9 was the designation for a nuclear powered version of the aircraft.
Piston Engines: Six Pratt & Whitney R-4360-53 radials
Power: 3,800hp each
Turbo jet engines: General Electric J47-GE-19
Power: 5,200lb thrust each
Span: 230ft 0in
Length: 162ft 1in
Height: 46ft 8in
Empty Weight: 171,035lb
Max take-off weight: 410,000lb
Maximum Speed: 411mph at 36,400ft
Cruising Speed: 391mph
Range: 6,800 miles with 10,000lb bombload
Guns: six retractable remote controlled fuselage turrets each with two 20mm cannon, two 20mm cannon in nose and two in tail
Bomb load: 86,000lb absolute maximum, 72,000lb normally